# std::time_get<CharT,InputIt>::get_weekday, std::time_get<CharT,InputIt>::do_get_weekday

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< cpp‎ | locale‎ | time get

Defined in header `<locale>` |  |
public: iter_type get_weekday( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t ) const; | (1) |
protected: virtual iter_type do_get_weekday( iter_type beg, iter_type end, std::ios_base& str, std::ios_base::iostate& err, std::tm* t ) const; | (2) |

1) Public member function, calls the protected virtual member function `do_get_weekday` of the most derived class.
2) Reads successive characters from the sequence `[`beg`,` end`)` and parses out the weekday name (possibly abbreviated), using the default format for weekdays expected by this locale, which is the same format as "%a" as used by the functions std::get_time, `time_get::get`, and the POSIX function `strptime()`.

If it finds abbreviated name, followed by the characters that are valid for the full name, it continues reading until it consumes all the characters for the full name or finds a character that is not expected, in which case parsing fails even if the first few characters were a valid abbreviation.

The parsed weekday is stored in the std::tm field t->tm_wday.

If the end iterator is reached before a valid weekday name is read, the function sets std::ios_base::eofbit in err. If a parsing error is encountered, the function sets std::ios_base::failbit in err.

### Parameters

beg | - | iterator designating the start of the sequence to parse
end | - | one past the end iterator for the sequence to parse
str | - | a stream object that this function uses to obtain locale facets when needed, e.g. std::ctype to skip whitespace or std::collate to compare strings
err | - | stream error flags object that is modified by this function to indicate errors
t | - | pointer to the std::tm object that will hold the result of this function call

### Return value

Iterator pointing one past the last character in `[`beg`,` end`)` that was recognized as a part of a valid weekday name.

### Notes

This function is usually case-insensitive.

If a parsing error is encountered, most implementations of this function leave *t unmodified.

### Example

Run this code

    #include <initializer_list>
    #include <iostream>
    #include <iterator>
    #include <locale>
    #include <sstream>
    #include <string_view>

    void try_get_wday(std::string_view s)
    {
        std::cout << "Parsing the weekday out of '" << s
                  << "' in the locale " << std::locale().name() << '\n';
        std::istringstream str{s.data()};
        std::ios_base::iostate err{std::ios_base::goodbit};

        std::tm t;
        std::time_get<char> const& facet = std::use_facet<std::time_get<char>>(str.getloc());
        std::istreambuf_iterator<char> ret = facet.get_weekday({str}, {}, str, err, &t);
        str.setstate(err);
        std::istreambuf_iterator<char> last{};

        if (str)
        {
            std::cout << "Successfully parsed, weekday number is " << t.tm_wday;

            if (ret != last)
            {
                std::cout << " Remaining content: ";
                std::copy(ret, last, std::ostreambuf_iterator<char>(std::cout));
            }
            else
                std::cout << " the input was fully consumed";
        }
        else
        {
            std::cout << "Parse failed. Unparsed string: ";
            std::copy(ret, last, std::ostreambuf_iterator<char>(std::cout));
        }

        std::cout << '\n';
    }

    void demo(std::string_view locale_name, std::initializer_list<std::string_view>&& data)
    {
        try
        {
            std::locale::global(std::locale(locale_name.data()));
        }
        catch (std::runtime_error const& ex)
        {
            std::cout << "Cannot setup locale: " << locale_name << "\n"
                         "Exception: " << ex.what() << '\n';
            return;
        }

        for (std::string_view const weekday : data)
            try_get_wday(weekday);
    }

    int main()
    {
        demo("lt_LT.utf8", {"Št", "Šeštadienis"});
        demo("en_US.utf8", {"SATELLITE"});
        demo("ja_JP.utf8", {"土曜日"});
    }

Possible output:

    Parsing the weekday out of 'Št' in the locale lt_LT.utf8
    Successfully parsed, weekday number is 6 the input was fully consumed
    Parsing the weekday out of 'Šeštadienis' in the locale lt_LT.utf8
    Successfully parsed, weekday number is 6 the input was fully consumed
    Parsing the weekday out of 'SATELLITE' in the locale en_US.utf8
    Successfully parsed, weekday number is 6 Remaining content: ELLITE
    Parsing the weekday out of '土曜日' in the locale ja_JP.utf8
    Successfully parsed, weekday number is 6 the input was fully consumed

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
LWG 248 | C++98 | `eofbit` was not set upon reaching the end iterator | sets `eofbit` if a valid weekday name has not been read

### See also

get_time (C++11) | parses a date/time value of specified format (function template)

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